A power tool of the above mentioned type is previously described in, for instance, U.S. Pat. No. 5,299,392. The pneumatic grinder shown in this patent comprises an exhaust air outlet passage 19 and a silencer 20 formed as a chamber with a number of outlet openings. At least in certain working positions of the tool, the exhaust air outlet flow through these openings causes dust and chips to be whirled up and circulated at the work site.
Another drawback of some prior art tools of this type is that in certain working positions of the tool the air outlet flow may hit the operator in the face and cause serious inconvenience for him or her, particularly when the air flow carries dust and particles derived from the working process.
A particular problem concerned with pneumatic power grinders is the low temperature of the exhaust air leaving the tool, usually -40.degree. to -50.degree. C. Such a cold air flow is not only very unpleasant but also unhealthy during operation of the tool. During operation of heavier straight type pneumatic grinders, moreover the operator very often is hit by this cold air flow on parts of his body or on his legs, because this type of machine is powerful enough to require extra support by, for instance, the operators leg or other body part.
In U.S. Pat. No. 2,080,973 there is described a straight type pneumatic grinder having a laterally directed exhaust air outlet 50 on the housing. Depending on the working position, the exhaust air from this outlet may cause an annoying air flow in front of the operators face which could be hazardous to the handling of the tool, or an unhealthy cold air flow may be directed to other parts of the operators body.
In U.S. Pat. No. 2,273,626 there is shown an electrically driven angle grinder provided with a fan boosted air cooling system including an air outlet on top of the tool housing. In certain working positions, the air outlet flow through this outlet may hit the operator in the face and cause serious inconvenience for him or her.